# Is the air pressure floating on us?

## Impulse Physics 2, textbook

First add the modeling clay to the water. It will sink because it displaces too little water. Then form a small boat out of the modeling clay. If the hull is big enough, the boat floats. You can also load it, as long as the total weight is less than the weight of the displaced water. V4 Plasticine boats Observe + examine + evaluate 91 Swim and sink 9 Why do ships swim? Have you ever wondered that a steel cargo ship can hold so much cargo and still float? Ships are very heavy, but their hulls are hollow and displace a lot of water. You can try that out at V4. As long as a ship is lighter than the displaced water, it swims. If a ship is overloaded and therefore heavier than the displaced water, it will sink. Air also has weight! Fish live in a sea of ​​water, we live in a sea of ​​air. Just as water has a weight, air also has a weight. The atmosphere surrounding the earth is up to 1,000 km thick. The weight of the column of air that rests on a surface is called air pressure. The air pressure is often given in millibars (mbar) and is around 1 013 mbar = 1 013 hPa at sea level. The air pressure, like the water pressure, acts on a body from all sides, including from below. The air pressure decreases with increasing altitude. On Mont Blanc, the air pressure is around half, on Mount Everest only a third of the air pressure at sea level is measured. A lower air pressure means that there is also less oxygen available. Mountaineers need to adapt their bodies well to these conditions. If the ascent is too fast, there is a risk of altitude sickness. The first signs are headache and dizziness. Only the descent into the valley helps. A climber measures his current altitude with a special barometer, the altimeter. M M M Materials Plasticine Bowl of water Cargo ships can carry large loads. The air pressure is indicated by a barometer. A can barometer is a small can with a vacuum inside, which is slightly depressed when the air pressure rises. Altitude sickness can occur on mountains above 2,000 m, such as the Grossglockner. For testing purposes only - property of the publisher öbv